Answering a call on the HTC Desire

Answering a call on the HTC Desire

I have the HTC Desire from cricket I am trying to change the way you can answer the incoming calles. Right now I have to slide either the red or green phone icon in to the little circle. My fingers are to big and it will not let me answer calls before the voicemail picks up. These call are important and some of them cant be returned with out havieng to leave a message and have them call you back. Is there a way to change this? Thank you
Erica